Hurricane Dorian

Waves crash in front of an American flag in advance of the potential arrival of Hurricane Dorian, in Vero Beach, Fla., Monday, Sept. 2, 2019. 

Hurricane Dorian officially came to an end on Sept. 10th, some 17 days after forming. The Category 5 hurricane was a behemoth of a storm that wrought destruction to the Bahamas, Atlantic Canada and the Southeastern United States. 

In anticipation of the storm, states of emergency were called in Florida, Georgia, the Carolinas and Virginia while first responders dispensed sandbags. Targeted evacuations were ordered for the islands of Grand Bahama and Abaco as residents were encouraged to gather at hurricane shelters. 

The Bahamas received the bulk of Dorian’s damage. The islands saw intense flooding and sustained wind speeds of 185 mph. The effects were magnified by the fact that the hurricane stalled over the islands, with its eyewall assaulting Grand Bahama and Abaco for nearly 24 hours.

Tens of thousands of Bahamians have been left homeless. The confirmed death toll currently stands at 50, but with 2500 people missing, the Bahamas government is sure that number will rise. 

Department of Oceanography and Coastal Sciences Assistant Professor Paul Miller recently completed a study of the long-term effects of severe storms like Dorian after the worst is over.

Looking at satellite images of Puerto Rico in the aftermath of Hurricane Maria, Miller reported a significant loss in vegetation, particularly leaves, and a transformation of the leaves' color from green to brown known as defoliation. According to Miller, this process may be at the root of decreased humidity, increased temperatures and flash-flooding frequency which can all occur in the weeks and months after severe storms. 

“Vegetation sweats, essentially," Miller said. "You have moisture from the plants emitted into the atmosphere, and more moisture present in the atmosphere means it is easier to make clouds and rain."

Defoliation cuts off this process and reduces moisture;without that ambient moisture, temperatures more readily rise. Vegetation also curbs heavy rainfall, and so with less of it around flashfooding is potentially a greater threat. 

Miller added that he expected the vegetation recovery process in Puerto Rico to take much longer than it did.

“The whole island went from brown to green again in two months. When it comes to these storms, Mother Nature is the best defense.” 

Miller said his research also made use of computer modeling based on defoliation and precipitation.

“Satellites give us information about levels of vegetation, rainfall and cloud cover," Miller said. "We can look at these data over time while monitoring landscape recovery.” 

When asked whether he thought these longer-term disturbances might be more pronounced in The Bahamas after suffering such a powerful hurricane, or whether anything could be done about them preemptively, Miller emphasized that meteorology is complicated.

“It really all has to do with the particular landscape," Miller said. "The Bahamas are small islands and the atmosphere is ultimately going to do what it wants to do. If it’s going to storm in Baton Rouge, it doesn’t matter if I mow my lawn that afternoon.”

 

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